Offshore LNG Generation

This is a guest post by Rockman, whose comments as an industry insider we have all come to appreciate. He believes that offshore generation of liquefied natural gas (LNG) has great potential.

Burning natural gas has always been viewed in a better light than burning crude oil by the public--more efficient in many home applications and less polluting in general. But it has been a hindrance and a source of frustration for the energy industry from the earliest days. A hindrance even today as billions of cubic feet of natural gas are flared or vented to the atmosphere as a by product of oil production. This is commonly the case with offshore oil fields where lack of pipeline infrastructure and/or local market negates the value of this useful commodity.

World image showing natural gas flares. Click for larger image.

The World Bank estimates 5 to 6 trillion cf (cubic feet) of natural gas are flared /vented yearly representing 400 million tons of green house gas emissions. This is equivalent to nearly one-third of the European Union’s annual natural gas consumption. Though this volume includes onshore operations (eastern Russia represents the largest single source), offshore fields are major contributors. Nigeria is the perfect poster child for such waste. At just $4 per thousand cf Nigeria is losing almost $100 million annually.

I’ve personally witnessed the nighttime glow from dozens of offshore flare stacks. Not only does this represent the loss of billions of dollars by this impoverished county but also a well documented health hazard to the population. I’ve seen the haze cloud stretch from horizon to horizon on otherwise cloudless days. And frustration in the form of proven NG fields which would be commercially viable to drill and produce except for the additional expense of a pipeline connection. Even today in the very mature Gulf of Mexico, with its huge pipeline infrastructure, many such reservoirs remain untapped for the same reason.

Off the northern coast of Australia is a proven field with an estimated 2 trillion cf of NG which has yet to be exploited due to the expense and difficulty of pipeline deployment. The Australian government estimates this field and others in the area represent more then 100 years of their country’s consumption. How many additional offshore NG fields may exist in areas which have been condemned for such exploration due to lack of transportation can only be guessed. The energy industry does not spend its capital surveying the amount of NG reserves around the globe that it cannot produce.

A common approach to exploiting NG reserves in areas with little or no market has been to liquefy the product and transport via tanker to energy hungry populations. In 2007 Marathon Oil began such operations in Equatorial Guinea and now weekly ships tankers of LNG from Nigeria’s neighbor to the EU. Such onshore plants are typically quite expensive ($1+ billion), but have often proved viable. But such operations still require pipelines to deliver the NG to the LNG plant.

Recent commitments to the research and construction of floating liquefaction plants may allow these wasted NG resources to be monetized. For over 20 years, companies have struggled to design against the problems generated by such an unstable floating system. Progress is now being made on offshore LNG floating liquefaction plants. Vessels are currently under construction and will be deployed near term.

One great advantage of such mobile plants is to exploit relatively small NG reserves. Typical onshore LNG plants require a huge feed stock to justify their construction. The capability to exploit smaller reserves and move on to other areas may be the most important aspect of this new technology. Just as the number of small oil accumulations dwarf the number giant oil fields so it is with NG accumulations.

As with the exploitation of all commodities, offshore LNG operations will expand as demand, and the prices develop with this demand, grows. Current low prices will certainly inhibit expansion of these efforts, but this dip in the price cycle will end. And as the world eventually accepts the premise of peak oil, it may come to see the utilization of these formerly wasted assets as a buffer to mitigate, to a degree and just for a limited time, the worst aspects many foresee with peak oil.

The nighttime photos of the world really show the flaring quite prominently.

Presumably someone has decided that the economics don't justify the expense of harvesting this energy source. Perhaps such decisions shouldn't be left up to "the market"?

I have been wondering if the plateauing of atmospheric methane since about 2000 till a bit over a year ago was partly because many releases are now flared or harvested. I would appreciate if any one has info on this.

On the main point, isn't there a bottle neck in the US in that we have relatively few ports that are equipped to handle shipments of LNG? Has this changed?

Is there currently a bit of a glut in NG globally(even if some of it can't make it to market for reasons just touched on)?

I might have thought they would use UV emission lines characteristic of flames, but even if some of those emissions pass through the atmosphere, it would take a specialized satellite. Instead, according to the huge PDF that is the "report" linked on the NGDC Earth Observation page, it looks like they use educated guesswork. To oversimplify, a gas flare is apparently a bright light that appears in a generally unexpected place such as over water, is steady for a period of time, but not too many years, is generally round in shape, and is identified with substantial effort by human analysts rather than by fully automatic means. So the map is probably laboriously produced, and pretty good but not perfect.

I have been wondering if the plateauing of atmospheric methane since about 2000 till a bit over a year ago was partly because many releases are now flared or harvested. I would appreciate if any one has info on this.

Flaring was always the most common thing to do.

Presumably someone has decided that the economics don't justify the expense of harvesting this energy source. Perhaps such decisions shouldn't be left up to "the market"?

It used to be that nobody could afford to let the ship stay put while it filled itself.

Some of the economic short comings are now being addressed politically. Royal Dutch Shell is a major player in this new field. But they are motivated by more then just monetizing an asset. They flare much of the offshore Nigerian NG and that gov't is preparing a new round of laws to penalize such waste. It is also becoming a bit of a PR problem for the Dutch oil men also. A recent protest at their headquarters included a 15' gas flare erected by the protesters.

TJ,

Two of the biggest problems have been minimizing the process equipment to retain efficiency while still being able to be deployed on a vessel smaller then an air craft carrier. It’s still a volume vs. time game for the most part. I wasn’t familiar with the LNG process but it’s much more complicated then just cooling and pressurizing the NG stream. The other problem involves mandatory shut downs when sea conditions become to rough. The shut down procedure is apparently complex and very wasteful. Too many involuntary shut downs and the process becomes unviable. For more details a quick Google turned up a good bit of tech info.

It probably makes more sense to ship the gas as methane hydrates. All this takes is relatively reasonable temperatures (~5 C under pressure to form hydrates, perhaps -20 C to keep them stable at sea-level pressure) and water. An insulated bulk-cargo carrier could transport large volumes of hydrate under refrigeration, and the only thing necessary at the far end is to scoop it out and melt it under pressure to release gas that's pipeline-ready after drying.

..About a third of the world's natural gas reserves contain high concentrations of contaminants and so are termed 'sour gas'.

..Low levels of contamination pose few problems but the higher concentrations in sour gas demand more intensive, more expensive processes.

..In the past Shell has tended to develop gas fields with low contamination, but still has 25 highly contaminated sites in production. Some 30% of Western Canada's reserves are sour, for example, but the scale of the challenge in the Middle East is far greater.

The UAE holds the world's fifth-largest gas reserves – approximately 214 trillion cubic feet – of which a large proportion is sour.

..Many factors push up the cost of exploiting sour gas reserves, most notably the fact that its contaminants make it highly poisonous, adding to health and safety concerns. It is also highly corrosive to iron, threatening flow lines and production equipment with sulphide stress cracking.
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Much more info in this article. Some natgas fields contain up to 35% H2S!.

I am not a natgas expert, but I believe if the natgas is sour [contains Sulfur], that this S must be removed before the compression stage or LNG stage, as the sulfur is quite corrosive and lethally toxic as hydrogen sulfide gas.

This requires much additional processing and safety equipment, especially on any next-generation floating natgas processing ship, because the workers would have no good survival options if the boat accidently became enveloped in toxic fumes. Hydrogen sulfide gas is heavier than air so it would tend to accumulate in any low spots on a ship. Even jumping overboard wouldn't help if you could not hold your breath long enough to swim out/escape the toxic layer.

I would assume a natgas processing ship would be regularly offloading the hot and molten sulfur [Amine + Claus Process] to regular scheduled cargo ships as sulfur is a key industrial Element, and at one recent point was selling for $900/ton. Thxs for any reply.

It can be a little unnerving working around H2S. I've been on wells drilling sour gas sections and you don't sleep well. An FSOP flaring 20 million cf of NG a day is a scary place too. But H2S can be a curse or a blessing. There have been times when the S market is high and operators make a nice bonus on the recovery process. I haven't watched the S market in some time. But $900/ton sounds likes a strong market. If Shell et al believe the market is stable they might push development on those sour fields where it was only the H2S content holding them back.

As a biologist that works with H2S, I have to wonder if there's an economical way to use microbes to remove it from the gas. There are many different sulfide oxidation pathways that yield different end products (not just elemental S but polysulfides, thiosulfate, polythionates, etc.) which are less toxic and potentially easier to remove.

Maybe Ashen but I suspect scalabilty and the time factor might be the difficulty with such an approach. A few thousand cf per day perhaps but 25 million cf per day is a lot to deal with. The NG has to be processed right then and quickly. No way to store any appreciable amount of NG in a gaseous state in an offshore environment.

Instead of processing the H2S to elemental sulfur, it may make more sense to process it to H2 by reaction with molten copper (the copper sulfide is regenerated by burning the sulfur off with air). The hydrogen can then be reacted with CO2 to make methanol.

I'd like to see the gas composition from some of these high-H2S fields. If they also produce a fair amount of CO2, then even more of the gas product could be turned into commodities.

Some LNG regassification projects have been approved in Houston, Freeport (by Houston), Louisiana, and Boston (and one offshore of Boston). Other prominent proposals in New York and Long Beach failed. So far none are taking routine deliveries, at least to my knowledge. This is because demand and price are higher in Japan and the EU, so most US facilities are getting enough to "chill down" the tanks, pumps, and pipes.

Most all NG in the Gulf of Mexico is captures except during drilling operations when flaring does happen and is only done on an emergency basis, so not much of a domestic demand for LNG liquifaction facilities here. There are issues such as remote areas or huge oil fields where there is so much NG that is cannot be stored in floating roof tanks. That said, the idea does sound intriguing.

As a side note, converting NG to LNG and back again to gaseous form take one hech of a lot of energy, although some companies have passive LNG regassification facilities - although many use vapor gas to combust in boiler heaters.

Yes, I recall reports that the drop in US LNG inports in '08 was due to competition by other buyers. I also recall LNG permits being denied in La and Al last year because the regulators didn't like the open loop method for cooling the NG. Don't know if that issue was ever resolved.

What caught my eye intially about floating LNG systems was a report about Brazil building a floating LNG regasification vesssel to handle imports. It didn't mention the possibiltiy of taking any associated NG from the big Deep Water oil play in LNG form but I suspect that thought has already crossed their minds.

And, yes, there were other reports I found that discussed the benefits of CNG over LNG in some circumstances. But I decided to start the conversation simply and allow all you well read types out their add to the discussion.

Rockman,
Thanks for this post.
The World Oil Magazine link is a good read.

Being a Stirling engine fan, I have been fascinated by Los Alamos Labs experiments with thermoacoustic Stirling engines for small capacity gas liquefaction - no moving parts, just a very loud noise in a heated box.

Stirling engines can work as heat engines or refrigerators. Join two together and you can make a device which you heat at one end and produce cooling at the other.

I don't know where they've got to now, but here are some links to papers on NG liquefaction from a few years ago:

If I remember rightly, the volume of LNG is something in the order of 1/600th of the volume of NG in its gaseous state.

For smaller, but nevertheless stranded, nearshore fields, would it make sense to compress rather than liquefy? I imagine this would be less energy intensive and could serve a purpose for otherwise stranded assets in the Gulf of Mexico, for example. I am specifically thinking about a floating compression vessel, rather than a floating liquefaction vessel.

Might this also be an appropriate solution for delivering NG from satellite fields to a centralised liquefaction plant? Here I am thinking of the Bonny Island facilities in Nigeria. If CNG could be delivered to those plants, rather than flared, it could then be liquefied for export...

Just an idea, and one that seems so simple that I imagine that the economics are not stacked in its favour. Anyone know the volume ratio of CNG to NG?

Rather than using a floating platform to produce LNG from the otherwise flared gas, would it be easier to use the floating platform to fix nitrogen via Haber-Bosch and produce fertilizer instead? Might be easier to ship? I have always wondered why this wasn't done. Does the natural gas have to be extremely pure?

You've five suggestions here: LNG, Compressed NG, Fischer-Tropsch, Haber-Bosch, and clathrates. Unfortunately, they all share the same disadvantage, they all require elevated pressures. So you have the same concerns about weather and equipment shutdowns for all five. Of the five, FT and HB usually are run at elevated temps so they would be somewhat worse in a confined space.

We don't know yet how these floating barges will cope with Cat 3+ cyclones. I see the local maritime college is testing a twin hulled design in their wave tank.

A conflict has arisen between Australia and fledgling nation East Timor over the choice of a floating oil and LNG platform as opposed to a seafloor pipeline. The big money claims that an underwater canyon prevents a pipeline to a land based facility on the nearby island. There may be some truth to the East Timorese claim they are being cut out of the loop. I guess cyclones are cheaper to deal with than royalty claims.

The Timorese aren't the only one wanting a piece of the pie. Some Australian politicians aren't too supportive of offshore plants. The coastal communities would much rather have the jobs/taxes that would accompany an onshore installation.

A standard LNG tanker carries 135,000 tonnes of LNG, which is about 6.5 BCF of NG. This would be at 1/600 compression. If CNG is 1/200 compression as suggested by Boof above, an LNG tanker could similarly carry about 2.2 BCF of CNG, which is pretty much the same amount flared daily in Nigeria.

Given the excess in LNG shipping capacity, it would seem to make sense for LNG shipping companies to add compression facilities on existing underused vessels and then rent them out for short haul services in Nigeria delivering product to liquefaction facilities. With the gas currently being flared, I assume it would be available at very low zero cost and would therefore be a pretty high margin business.

Even if liquefaction is already operating at full capacity (as I assume it is), it would still be a profitable venture to deliver the CNG to European / USA markets. At curent charter rates of $45,000 per day, the 30 day round trip from Bonny Island to Freeport, LA and back would take about 30 days, generating $1.35 million in revenues. A shipping company would therefore only have to make a net margin of about $0.60 per thousand cubic feet to exceed its charter profitability rates....

Someone tell me where I am going wrong, this makes way too much sense....

You're going wrong by assuming that LNG tankers could be used for compressed NG. The LNG is stored at low pressure in liquid form. They could not take 200 atmospheres, that takes a heavy steel receiver bank.

Good catch bunyon. Like most Americans I sometimes miss those pesky metric units.

As far as expanding onshore Nigerian operations I get a very strong impression there's little interest by the companies. Just getting too unstable. Even offshore operations aren't completely safe. The captain of an oil field service vessel was just killed by rebels/pirates yesterday.

Probably not wrong. But I suspect the combination of the credit market and a sense of an increasing volatile NG market in general could be holding the players back. I have a suspicion that we’ll be seeing a much more volatile domestic NG market as well as for oil. That such instability may the persistent signature of PO as we go forward.

Yes, I've read your comments about the drilling shut downs in UNG plays - is that public domain knowledge other than on TOD?

If Europe and USA attract a lot of spare LNG this summer, this will exacerbate the situation and shut down even more drilling. As in oil, this will just make the supply crunch so much worse when it happens.

The big question is when that will be, for both oil and gas. I foresee a lot of volatility

How good is the geology of offshore gas?
South Pars/North Dome (Iran-Qatar-1800 Tcf), Gorgon(60 Tcf+25% CO2) and Shtokmann(200 Tcf) are 'super-giants'. We know that offshore costs more. It only makes sense that the estimates would be grossly exaggerated.

South Pars/North Dome only produces a 4Tcf per year and the Iranians have had to import natural gas from Turkmenistan.
Strange.

The bottleneck in the LNG supply chain is in liquefaction, not transportation. That is why shipping companies like Golar are converting tankers to floating regas vessels, their current fleet is underutilised, particularly in summer months where NG demand is lower.

Offshore geology isn't too tough. In fact, with the large amount of seismic seen over most offshore fields it can be pretty accurate. OTOH, you have to watch out for those wildly optimistic exploration geologists as well as their lying bosses. But don't take my word for it. I'm just a bitter old development geologist who spent a life time explaining why I failed to drill up all those reserves others had promised.

my recollection is that about 30-33% of the BTUs in the natural gas are used in liquefying and transporting it - do you have links or refinement on this data? (I think I got it from Simmons way back.) Thx.

I don't recall anyone offering the full cycle BTU expense but from the bits and pieces I've seen your numbers are in the ball park. I imagine one key will be the cost of this throw away NG. The lessor might accept not getting paid for flare NG but if the operator starts monetizing this commodity and the original lease isn't clear on the royalty split I can imagine a significant tug of war between the parties.

I have also heard those numbers for LNG. It will come down to financial and energy cost and profit, but what is the energy cost of GTL? Diesel is easier to ship than LNG and does not need specialized ports. Diesel (and aviation/jet fuels) are the "essential" fuels, running the military, trucks, buses, farming, fishing etc etc.

What kinda leakage can be expected from something like this? Methane has a GWP of 72 over two decades, so just one molecule traps as much heat as 72 Carbon Dioxide molecules, and even just a little over one percent leakage would double the GHG emissions associated w/ it.

These people seem to be on the right trackhttp://www.methanegasdetectors.com/
When natgas runs low I believe we should make synthetic methane using organic carbon and a hydrogen source. Better than abandoning the gas grid altogether.

It depends on the application. We could replace it's domestic use w/ a third or less of the renewable energy uses via heat pumps and so on. Best leave it as a feedstock for industrial uses since it's a lot easier to use rather than have renewables and/or nukes synthesize stuff to fill it's place. IIRC all the flaring is done because of it's GWP. Better to have one CO2 running around w/ a GWP of 1 after we burn the CH4 than to have the CH4 running around w/ a GWP of 72 over the next couple decades.

What about nitrous oxide from fertiliser? I believe it has GWP exceeding 300. The prospect for methanated syngas needs a lifecycle analysis. Plenty of unmonitored methane will come from cow farts because we eat too much meat and dairy. Those electric heat pumps will use a lot of fossil energy to build and install. Food processors and hospital laundries seem to like the 'wraparound' heat of gas rather than electric. And ..(this is big).. I predict the motoring public won't take to electric cars. After the next oil price rebound people will want cars that neither need oil nor frequent charging. That says compressed gas to me. Like old railroads once the gas network is torn up it may be impossible to repair. Gas is also a backup to electricity in the form of CHP and can share the heating burden in cold snaps.

I have increasingly heard environmentalists mention cow farts as a significant source of GHG, and since you decided to mention them, I am wondering if you have any quantitative data on the subject. I agree there are ALOT of cows, but there don't seem to be THAT many... in other words, from a qualitative perspective I don't believe it. Also, why do you forsee a problem with the adoption of EV's?

It is thought that more than 50% of New Zealand's greenhouse emissions are from enteric methanehttp://news.nationalgeographic.com/news/2002/05/0509_020509_belch.html
If I recall 15-20% has been cited for Australia. Farming was deliberately left out of the Australian emissions trading scheme for that reason. Then the scheme was watered down so even CO2 wasn't bad anymore.

On EVs I believe very few of the world's 800m motorists have any inkling yet of their limited range and cost. People want to drive 500km on one 'fill up', to whoosh over mountain passes, tow trailers and carry heavy luggage in a car costing half their annual salary. I suggest those who say EVs suit them could bus or bike instead.

Nitrous Oxide only tends to occur in soil where we see Oxygen depletion, so it's not strictly related to synthetic fertilizer production and instead comes from improper application in this context, although it's definitely something to minimize via a change in fertilizer application. There's definitely a large GHG increase associated with livestock, both from methane and from all the feed grain required.

Your statement about electric heat pumps seem unfounded. According to this a ~100lb air conditioner (AKA a heat pump) requires ~700kWh in it's manufacturing for a large window unit, so assuming a ~3000kWh heat pump/AC including installation should do. The average American uses ~15000kWh of energy per year for heating, and be it electric, nat gas, fuel oil, or otherwise, and this requires more FF energy that it provides in terms of heat.

Even in unfavorable conditions a heat pump will still have a COP of around 2 (6 seems to be the best), meaning it will only need half of the same amount of energy, probably less, to provide the same amount of heat. Even assuming we continued to use FFs, cutting use by half would more than save the embodied FF energy needed for heat pump construction within the first year alone. As a secondary benefit, we can power heat pumps via renewables, w/ virtually no Carbon emissions. This isn't something we can do with nat gas or fuel oil heating, and it's twice as efficient as ohmic heating. Heat pumps aren't anything new for large buildings either, it's just that HMOs over here don't seem to be interested in saving money and lives, just the profit margin, kinda like FF producers. In fact, I imagine that there's a synergistic effect via increased pollution and other externalities via increased FF use/profit, and increased health care requirements/profit. Economics is not a zero sum game. :(

As for electric vehicles, I imagine that market penetration for pure EVs will be relatively small, with HEVs commanding the largest share of the market, especially since companies are approaching the point where their margins are the same as conventional cars, followed of course by PHEVs, and in general, smaller, more efficient vehicles. It'll probably be a gradual process. Unlike railroads, the NG distribution network tends to follow established energy corridors AFAIK, so even if we minimize use, the corridor won't get built over. Rail corridors otoh, which tended to be totally unused once rail kicked the bucket in that area, weren't so lucky.

Just like gas is a dispatchable backup for electricity generation, so is waste incineration. And unlike nat gas, waste incineration results in a net benefit in terms of lower GHG emissions compared to letting the trash decompose in a dump, which will also eventually leak. Overall, I think that if we are serious about addressing GCC, the days of nat gas for heat/electricity generation, just like coal and oil, are numbered. If we're serious, which is a pretty big if. ;)

When prices swing back up (or even if they continue to be volatile), I think the EV market could pick up. Multi-car families are the norm. Having an EV as the second or third car for everyday errands within a certain radius could easily become the norm quickly. But this would obviously be fascilitated by lower speed limits on many roads, something that should have happened already if we were living in any thing remotely resembling a sane society.

We have a Zenn which we bought for $11,000. We use it for almost everything, but we've kept our Internal Combustion Engine car for back up, longer trips...I can't remember the exact figure or the source, but for most urban dwellers some 80% of their car trips are within 10 miles of home.

But you are right that a century of ever more available energy has left people with bizarre expectations about what they "need" in a car (even if such capacities are rarely if ever used).

Last I heard there was an entire industry devoted to getting people to buy and do things they wouldn't otherwise buy or do. Perhaps if a smidgen of this propaganda machine were directed toward getting people to do and buy things that might give us some remote, glimmering chance of a survivable future instead of always persuading us to buy useless crap and enormously and needlessly harmful contraptions, we might get somewhere.

rolph -- Good point I didn't bring up earlier about venting NG. I couldn't find an estimate of vented vs. flared NG. AS you point out vented NG is a far worse action then flaring. Whatever leakage (SOP and major accident) we'll still be better of utilizing the NG via LNG then continuing with current practices IMO.

Better off depends on the case. If it's all being flared, and when using it we see 3% leakage instead of no or very little (less than 1%) leakage, than GHG emissions associated w/ it will triple, not better off in that case. If leakage is very low in general, less than 1%, than it shouldn't be too bad, only increased GHG emissions from natural gas by ~30-60% over the next couple decades. In general I think that addressing GHG emissions, so it wasn't leaked and had to be flared would be the best option. No reason to create more busy work for ourselves down the line.

Anyway, in terms of methane emissions, if 99% of it were leaked like you mentioned instead of flared in Nigeria, world GHG emissions would increase by about a percent, just based on that change in one country. If this was done around the world, GHG emissions would probably increase by billions of tons of Carbon Dioxide equivalent.

I get your point now rofl. I thought you were only talking about the vent gas going LNG. True: let enough converted flare gas leak and you're not improving that aspect of the situation. And that leads to another potential thread you might want to pursue: what is the nature of methane leakage today globally and should we be focusing as much or more on it then CO2?

Lesse, methane emissions are about 10-15% of what's responsible for radiative forcing, and of that ~5% of it is associated with flaring, so we're maybe looking at a percent of the total associated w/ flaring. The best thing to do wrt to GCC overall is minimize fossil fuel energy use.

It varies with the NG saturation in the oil and the reservoir drive mechanism. In a pure water drive the NG cut stays relatively constant. On the other end of the spectrum are pure pressure depletion oil reservoirs. In this case it's the expansion of the NG as pressure is lowered that drives the oil out of the reservoir (called the bubble point). But once the NG expands to max the reservoir drive stops and the oil stops flowing -- typically very low recovery rates.

In NG injection effort the gas forms a cap on top of the oil and helps maintain pressure to push the oil out. Very little of this NG saturates the oil directly. What NG is separated from the oil is usually reinjected. Once the oil is recovered they recomplete the wells higher and recover the NG at that time.

By combining an offshore wind farm with stranded gas fields and small generator platform has several advantages. The same process could be applied to currently flared gas. With the offshore wind having a capacity factor of 0.35ish the gas turbine would only need to operate with capacity factor of 0.5 and the combined system would provide continuous power. Eventually as the gas fields become depleted they would become ideal for compressed air storage making use of the off peak wind power.

Interesting ideas OMG. Just one little point: depleted NG reservoirs could never be used for O2 storage. There is always a small amount of NG left behind in a depleted field. Compressed air is dangerous enough but adding some hydrocarbons to it is a real killer. In fact, if the reservoir is deeper than 5000' or so the O2 will spontaneously oxidize the NG in place. This is actually the basis for a little known secondary oil recovery process called in situ combustion or "fire flood".

But one could cycle any other gas (N2, NG) and achieve your goal I believe.

damn those externalized costs. what we are seeing here is a world consuming about 70 million barrels of crude oil per day and we dont know what to do with that "excess" gas.

i can tell you for sure, the answer is not to just light a match. if "regulators" didn't allow flaring, wouldn't the free market find a way to produce the oil without flaring ?

and i see an opening here to post a rant about what is going on in the saudi arabia of the missouri river badlands(that is, according to the likes of rush limbaugh). the state of north dakota industrial commission concluded that allowing flaring of ng would prevent waste because of some contorted gobblygook about the value of the crude oil exceeding the value of the natural gas !

well an unentended consequence of this brilliant decision is that because of the local glut of oil in the williston basin, oil is selling at a deep discount to wti, on the order of $ 11/ barrel(28%) for the entire basin. i think they shot themselves in the foot.

the 21st century ? maybe we should look back at the lessons of the 20th century, spindletop comes to mind.

So true elwood. As I've said before I'm a ratioanl libertarian. But there are reasons for gov't regs in the biz sector. The ND flare rules are the same BS we had in Tx in the good ole bad days. Make them utilize the NG or shut the oil in and they'll find a way. If the costs kills the oil play then so be it. But when oil is priced high enough they'll swap some of the profit for whatever method they'll need to handle the NG honorably.

I remember gas vents on local donkey wells, sometimes flared but often open vented. Setting off the vent plume to cause minor explosions was rural fun for "naughty kids". Never heard of any major injuries or fires, but it seemed dangerous. Sometimes flares would go out, and they'd just vent the gas until the local jobber paid a visit and decided to re-fire it.

Gas was free then -- if you lived on the property and would run the line they'd let you have the gas (or maybe it was part of a lease deal?). Others ran the well pump off "popper" motors if they were rural enough so at to not irritate anybody. IIRC they "popped" about 50% of the firing cycles, so probably a good bit of that gas vented too.

yep...the old days Paleo. North of Houston is Tombal, TX. Ages ago Exonn developed an oil fld there with lots of associated NG. Since the field was under part of the town XOM gave the NG to the city for free. Better then just flaring it off. Eventually the fld depleted and XOM stopped delivering the NG, of course. And then the city filed a lawsuit against XOM, of course. Not sure how that turned out but file under "No good deed goes unpunished".

Another real story of NG "harvesting". On one of my NG wells about 25 years ago a rice farmer had secretly tapped our field line and ran the stolen NG to his rice dryer just down the road. My production foreman couldn't figure out why the meters wouldn't balance so one day he pressured up the system to find the leak. The higher pressure led to the rice dryer blowing up and burning down. Of course, the farmer immediately ran down to my hand and began raising hell.

Question: For (esp. onshore, perhaps offshore) stranded gas recoveries too small to justify LNG infrastructure, would it be justified to install CH4 --> H2 + H2 liquifying equipment? The concept is to develop LARGE H2-supported dirigibles which use H2 turbines for propulsion. Each one could loft 500 tons of liquid hydrogen (+ 100 tons tankage, crews) in disconnectable tanks along bottom. Delivering 450 tons H2 from mid Africa to Germany would cost 50 tons H2 as fuel on an 8 day round trip, leaving 450 tons saleable H2 net in Germany. The dirigible would be capable of moving the skidded H2 production equipment from site to site as conditions warranted. I've discussed plan with Praxair they say the H2 production part is readily available and economical. Remains to actually produce the 600 T cargo capy. carbon fiber dirigible (I have a strategy covering that....), and determine if BMW can sell enough of those H2 burning cars they demonstrated.

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